Spurious component reduction

A wireless transceiver, comprising:

• a transmitter operable to transmit a modulated carrier signal, the transmitter including a communications circuit, the communications circuit comprising:
• a wideband polyphase filter operable to filter an input signal having an associated first frequency to produce a filtered signal, the wideband polyphase filter having poles corresponding to a first filter frequency and a second filter frequency, the second filter frequency being substantially different than the first filter frequency, wherein the first filter frequency corresponds to a desired signal in the input signal and the second filter frequency corresponds to a spurious component in the input signal;
• and
• a mixer operable to mix the filtered signal with a local-oscillator signal at a second frequency to produce an upconverted signal, the second frequency being substantially an integer multiple of the first frequency.

A wireless transceiver, comprising:

• transmitting means for transmitting a modulated carrier signal, the transmitting means including upconversion means, the upconversion means comprising:
• filtering means for filtering an input signal having an associated first frequency to produce a filtered signal, the filtering means having poles corresponding to a first filter frequency and a second filter frequency, the second filter frequency being substantially different than the first filter frequency, wherein the first filter frequency corresponds to a desired signal in the input signal and the second filter frequency corresponds to a spurious component in the input signal;
• and
• mixing means for mixing the filtered signal with a local-oscillator signal at a second frequency to produce an upconverted signal, the second frequency being substantially an integer multiple of the first frequency.

A method for reducing spurious components in an upconverted signal, the method comprising:

• filtering, using a filter, an input signal having an associated first frequency to produce an in-phase filtered signal and a quadrature filtered signal, the quadrature filtered signal being substantially ninety degrees out of phase with the in-phase filtered signal at a first filter frequency and at a second filter frequency, the second filter frequency being substantially different than the first filter frequency, wherein the first filter frequency corresponds to a desired signal in the input signal and the second filter frequency corresponds to a spurious component in the input signal;
• mixing the in-phase filtered signal to a second frequency to produce an in-phase upconverted signal, the second frequency being substantially an integer multiple of the first frequency;
• and
• mixing the quadrature filtered signal to the second frequency to produce a quadrature upconverted signal.

A wideband polyphase filter, comprising:

• a first filtering section to provide one or more poles corresponding to a first frequency;
• and
• a second filtering section coupled to the first filtering section to provide one or more poles corresponding to a second frequency, the second frequency being substantially different than the first frequency,
• wherein the first frequency corresponds to a fundamental frequency of an intermediate-frequency local-oscillator signal;
• and
• the second frequency corresponds to a frequency of a spurious component.

A method for reducing spurious components in an upconverted signal, the method comprising:

• first mixing, using a mixing device, an input signal to a first frequency producing an intermediate signal;
• thereafter mixing the intermediate signal to a second frequency producing an upconverted signal, the second frequency being substantially different than the first frequency;
• and
• selecting the first frequency and the second frequency such that a spurious component generated in the first mixing falls, when upconverted, on a same frequency as another component in the upconverted signal.